If you cleared out all the tapes from most advertising agencies around town, their offices would probably collapse. Stacked floor to ceiling, these tapes and their boxes have become, you suspect, vital structural bulwarks to the buildings of adland. Ditto to the traffic departments of commercial broadcasters.
In this digital age, it is worth remembering that some parts of the business are anything but virtual - commercial television remains one of the few businesses where motorcycle couriers are still an important part of the communications infrastructure.
It is true that an electronic means of distributing commercials to broadcasters has been in place for the past decade. Called Playout, it has been mainly the fiefdom of ITV and has had other drawbacks, from the point of view of non-ITV broadcasters.
For a start, it isn't flexible or interactive - two or three times a week, new TV commercials are merely dumped on the system. If you miss a transmission, you cannot ask for a repeat. Which is linked to another weakness - the material is sent in a video format rather than over a digitised data connection.
But two companies - Adstream and IMD - are determined to drag the distribution business into the 21st century. Adstream was launched in Australia in 2001 and Adstream Europe followed in 2003.
Andy Hopkinson, Adstream's managing director, says: "Australia is now fully digital - it's probably the most advanced broadcast market in the world in that respect. It has to be - the distances there are so huge. It's also a market controlled by a small number of media owners, which also helps in developing of this sort of thing."
Since its launch, Adstream has managed to take more than 50 per cent share of the Australian market and has used its relationships and experience to build a bridgehead in the UK.
Its most prominent UK customer is BSkyB, a broadcaster that was more than ready to go digital.
For a start, it had been effectively excluded from the Playout system by the UK commercial broadcasting establishment.
And, of course, by driving an explosion of new channels, SkyDigital has made the world of commercial television an infinitely more complicated place.
Conventional distribution systems were never going to survive for long in the digital television age. It is not just that there are now more than 300 channels in the UK - a number that continues to rise by the week.
Audience fragmentation brings even greater complexities.
For instance, advertisers are now using TV increasingly as a direct-response medium and, as a consequence, they may be using different executions at different times of the day. When this is done on an international basis, the complexities multiply many times over.
Adstream is now working with Sky Italia to manage the internal distribution of communications between Sky Italia and seven new broadcast partners in Italy, which will be broadcast out of Rome, Milan and London.
But consider the average mainstream multinational packaged goods company.
Some of its brands may have one basic execution that is repurposed and dubbed for various different markets. The ability to process and distribute such ads from a central hub is always going to be a cost-effective option.
Not all broadcasters have gone completely digital in their traffic departments - but even ITV is now looking at this, while five and Channel 4 have begun taking some copy digitally.
Arshad Rasul, the director of engineering and technology at the Welsh language channel S4C, says: "Digital distribution is clearly the future - I just wish it were more widely used. It's better targeted and flexible - if you want just one ad, you can get one ad.
I am convinced that the market will evolve quite substantially in this direction over the next couple of years."
And the world of commercial television is continuing to become more integrated on an international basis - even in the most isolated of locations.
Peter Faye, a project manager at RTE in the Republic of Ireland, explains: "We are qualified enthusiasts when it comes to digital distribution. We have had some teething troubles that are probably down to our own inexperience - but there is absolutely no doubt you get the stuff quicker.
"And we have a sister station in Galway. It's a remote area. We have now linked the system down there with Adstream, which is a big thing. Getting tapes to Connemara is difficult enough at the best of times."
THE SKY VIEW - Steve Hutchinson, Head of commercial traffic, BSkyB
When BSkyB launched in 1990, we had to convince advertisers to courier their ads, at their own expense, to our headquarters in Osterley, Middlesex.
They had to send two beta SPs and one VHS of each commercial they wanted to transmit over our then four channels.
More regularly than I am prepared to admit, the commercials that were delivered to BSkyB would disappear into what became known as the Bermuda Triangle. This was the BSkyB copy triangle, made up of GR, VR and NR (Goods Room, VT Room and the Sky News Room) and all the expanses in between.
Agencies' rotation instructions, which contained all the necessary metadata and authorisation to broadcasters to transmit commercials, would also occasionally disappear into this void - that is, behind fax machines and under filing cabinets.
Once BSkyB launched its digital platform and services in October 1998 - and its sales arm had secured significant external sales representation from other broadcasters - we were selling airtime on more than 150 channels a day.
Receiving commercials in denominations of one or two at a time on the back of a courier was now causing fundamental problems for our commercial copy operations. This was compounded by the mammoth increase in the number of commercials that we were trafficking each week, which, on some occasions, pushed our commercial operations near the point of critical overload.
Furthermore, we were under increasing pressure from advertisers, who were keen to minimise the cost and waste involved in supplying us with commercial tapes.
Transforming BSkyB's commercial tape delivery into a digital process, in partnership with Adstream, was the natural solution. The digital revolution has completely transformed the TV landscape in the UK, and digital commercial delivery will have a similarly metamorphic effect on adland.
I can hold approximately 5,000, 30-second commercials on a server box at any one time before having to worry about archiving. My commercial traffic team has the ability to access metadata relating to the commercial along with rotation instructions that have been previously input by the agency.
The fact that we were the first broadcaster to receive commercials digitally complimented BSkyB's ambition of being the market leader. And there are huge rewards, including the rapid speed at which commercials reach our playout facilities. We know exactly when commercials have arrived on site and I can even receive pager alerts.
The technology also means that we now have the ability to access associated metadata delivered with the commercial, can be confident that broadcast quality checks have already been conducted and that the material is technically ready for transmission.
And because we can now view the commercials on our desktops, we have benefited from workflow efficiencies and are able to request additional copies of commercials in an instant if necessary.
The system is fast, user-friendly, reliable, cost-effective, efficient and has significantly strengthened our relationships with advertisers, clients and, especially, our creative agencies.